Digital Commons Network^™

Sensors Forph Based On Swelling And Reflectivity Of Derivatized Polystyrene Beads And Membranes, Li Zhang

Doctoral Dissertations

Kraton-modified amine-derivatized poly(vinylbenzyl chloride) beads prepared by suspension polymerization are sensitive to pH. They swell in acid due to protonation of amine groups and shrink in base. Polymer swelling generates a measurable swelling signal that is related to the concentration of hydrogen ions in solution. The sensor responded to pH in the range from 6.0 to 10.0. Bead size, level of porogenic solvents and Kraton G1652 affected the magnitude of sensor response and response time.

Diethanolamine derivatized poly(VBC) membranes formulated with a small amount of Kraton G1652 reflect light. At low pH membranes turn clear. The observed optical change is …

Construction Of An X-Band Electron Nuclear Double Resonance Spectrometer And Partial Characterization Of An Iron Nitrosyl Complex Of Transferrin, Pamela Marie Proulx-Curry

Doctoral Dissertations

An X-band Electron Nuclear Double Resonance (ENDOR) spectrometer was constructed, tested at both room and liquid helium temperatures, and characterized at liquid helium temperature using a vanadyl-imidazole standard.

An iron nitrosyl complex of transferrin was studied. Three methods of generating nitric oxide gas were tested and resulted in no differences in product formation. The g-factors for the rhombic complex--prepared with and without carbonate addition to the buffer--were determined. For the complex prepared with carbonate g$\sb{\rm x}$ = 2.052, g$\sb{\rm y}$ = 2.028, and g$\sb{\rm z}$ = 2.013. For the complex prepared without addition of carbonate g$\sb{\rm x}$ = 2.051, g$\sb{\rm …

The Purification And Characterization Of An Extrapallial Fluid Protein From The Mollusc, Mytilus Edulis, Stephen Joseph Hattan

Doctoral Dissertations

Shell deposition within the bivalve mollusc Mytilus edulis is regulated by the macromolecules of the extrapallial fluid (EP fluid). These mineralization regulating macromolecules are thought to be responsible for the nucleation, growth regulation and growth cessation of the CaCO$\sb3$ mineral crystals that will inevitable constitute $\geq$95% of the mature shell.

This dissertation presents the results of the purification and characterization of the major EP fluid protein of the bivalve Mytilus edulis. The major EP fluid protein was determined to comprise 56% of the total fluid protein and to consist of 7.25% by weight carbohydrate. The protein was purified though a …

Formation And Fate Of Methyltin Compounds In The Great Bay Estuary (New Hampshire), Anne M. Falke

Doctoral Dissertations

Methyltin compounds (MeSn), which are not of anthropogenic origin, are common in estuaries, particularly in the marsh grass Spartina alterniflora. During the 1989 growing season, S. alterniflora leaves collected from three locations in the Great Bay Estuary were analyzed for MeSn and inorganic tin by hydride generation/atomic absorption spectrophotometry (HG-AAS). Total MeSn concentrations showed a sharp increase early in the season, reaching a maximum on May 23, then gradually decreased. Statistical calculations verified that date was a significant contributor to the observed variance, while location was not.

Two years later the seasonal study was expanded to include below ground portions …

Development Of Q-Band Epr/Endor Spectrometer And Epr/Endor Studies Of Dinitrosyl Iron Model Complexes, Wenge Wang

Doctoral Dissertations

A robust yet sensitive Q-band (35 GHz) cavity has been designed for routine variable temperature EPR (electron paramagnetic resonance) and ENDOR (electron nuclear double resonance) measurements down to 2 K. It consists of an aluminum or brass (plain, silver or gold plated) ribbon imbedded in a cylindrical epoxy or epoxy/quartz composite with a tunable piston at the bottom. The cavity has all the advantages of the traditional silver wire-wound cavity often used for Q-band measurements but is much more robust and easier to construct. The cavity suppresses degenerate resonant modes and minimizes wall eddy currents induced by field modulation. With …

Interactions Of Conjugated And Unconjugated Bile Salts With Model Phospholipid Membranes: Vibrational Spectroscopic Studies, Kimberly Ann Parthum

Doctoral Dissertations

Bile salts play important roles in digestion and the treatment of diseases. Few studies have been performed to determine, at the molecular level, the interactions of individual bile salt species with cellular membranes. Vibrational spectroscopy provides a noninvasive approach for characterizing the structural changes occurring within the lipid matrix due to their association with bioactive molecules. The frequency of the methylene stretching modes in the infrared spectra of the lipids comprising the membrane, as a function of temperature, yields information on the intra- and interchain order/disorder of the lipid matrix, the stability of the membrane, and the cooperativity between lipid …

Investigation Of Pd(A)(20)Pd(T)(20) In The Analytical Electrophoresis Apparatus, John Oliver Wooll

Doctoral Dissertations

The analytical electrophoresis apparatus (AEA) is capable of generating and monitoring the electrophoretic migration of macroions. The oligonucleotide pd(A)$\sb{20}\cdot$pd(T)$\sb{20}$ was use as a model to compound to evaluate the range and validity of AEA measurements under a variety of electric fields and solvent conditions. A broad range of electric fields yield consistent, reproducible values. The charge determination from different procedures, steady state electrophoresis (SSE) and electrophoretic mobility, have not been consolidated into a consistent theory but advancements in the scope and understanding of the AEA's potential have been made. The apparent charge from the AEA measured electrophoretic mobility, $\mu$, of …

Polymer Substrates For Optical Chemical Sensing, Michael Thomas Rooney

Doctoral Dissertations

Membranes for chemical sensing based on changes in light reflectance from amine-modified, porous, rubber-toughened poly(vinylbenzyl chloride-co-divinyl benzene) were prepared by bulk free radical polymerization. Xylene and dodecane were used as porogenic solvents and solutions were prepolymerized to viscous solutions prior to forming membranes. The crosslinked membranes are turbid and scatter light when unswollen. They swell in response to increases in hydrogen ion concentration, causing the membrane to reflect less light. Turbidity is ascribed mainly to scattering by water-filled macropores within the amine-functionalized membranes. Swelling decreases the refractive index of porous, hydrated polymers with 2% crosslinking by approximately 0.04 units, bringing …

Evaluation Of Polymer Coated Attenuated Total Reflection (Atr) Elements For The Analysis Of Organic Compounds In Aqueous Solution, Marc C. Ertan-Lamontagne

Doctoral Dissertations

A significant limitation of ATR/FTIR for the analysis of aqueous solutions is the relatively high bulk concentration of analyte required. One approach to improving the detection of an analyte is to incorporate a thin polymeric phase at the surface of the ATR element. The purpose of the polymeric phase is to extract the analyte of interest and concentrate it within the depth of penetration of the evanescent wave. Utilizing a very high molecular weight poly(vinyl chloride) phase the time necessary to reach equilibrium for a 0.05% (v/v) nitrobenzene in a 1.5% (w/v) methanol/water solution was over 60 minutes. A study …

Chiral Separations Using Bile Salts In Capillary Electrophoresis, James George Clothier

Doctoral Dissertations

Micellar electrokinetic capillary chromatography (MECC) using surfactant solutions containing bile salts, polyoxyethylene ethers and methanol was used to produce chiral separations. A capillary electrophoresis instrument was assembled in the laboratory. Initial testing and optimization of the instrument involved the separation of organic acids using capillaries zone electrophoresis techniques. Polymer coated capillaries were prepared and tested in the instrument. Bile salt solutions were characterized by viscosity and nuclear magnetic resonance. The effects of various solution conditions, such as pH, ionic strength and concentration of bile salt solutions on chiral resolution were investigated by MECC. Enhancement in chiral resolution was obtained using …

The Development And Applications Of A Capacitively Coupled Microwave Induced Plasma Evolved Gas Analysis Instrument, Stephan Michael Koza

Doctoral Dissertations

The scope of this dissertation covers the development and subsequent utilization of an Evolved Gas Analysis (EGA) instrument using atomic emission from a microwave induced plasma source (MIP) as a detector. The majority of the effort during the course of the project was directed toward the design of a new plasma source that has a capacitively-coupled resonance cavity and a sheathed torch, and resolving a number of technical and scientific problems. This discourse also includes an account of the devices developed for use with the instrumentation.

Three applications are demonstrated. The detection, quantitation, and speciation of 10$\sp{-4}$ to 10$\sp{-6}$ gram …

Characterization Of Radical Formation And Iron Oxidation/Hydrolysis During Iron Deposition In Ferritin, Yu Chen Barrett

Doctoral Dissertations

The functional roles of ferritin H and L subunits in ferrous iron oxidation and ferric iron hydrolytic polymerization were studied by combination of electrode oximetry and pH stat utilizing horse spleen and recombinant human H and L ferritins. Previous work has investigated ferrous ion oxidation kinetics, but no information on ferric core formation and its relationship to ferrous ion oxidation had been obtained. The kinetic pattern of iron oxidation/hydrolysis in H-chain homopolymer ferritin showed that the rate of iron hydrolysis is regulated by the rate of iron oxidation, and that both follow the iron ferroxidation pathway. In the early stage …

Polymer Substrates For Use In Fiber Optic Sensors: Suspension Polymerization Of Kraton G1652 Modified Poly(Vinylbenzyl Chloride), Vicki Lynn Conway

Doctoral Dissertations

The polymerization of Kraton G1652 modified poly(vinylbenzyl chloride) in the presence of xylene and dodecane is complex. Scanning electron micrographs and porosimetry data suggest that as polymerization proceeds, the forming poly(vinylbenzyl chloride) and the porogenic solvent separate into distinct aromatic and aliphatic phases, respectively. The Kraton G1652 acts as a surfactant between the dodecane and the forming polymer swollen in monomer, and is directly involved in stabilizing the interface. Increasing the Kraton G1652 increases the surfactant content of the monomer mixture which decreases the surface tension between the forming polymer and the dodecane during polymerization, resulting in a morphology consisting …

Fiber Optic Chemical Sensors Based On Polymer Swelling And Shrinking, Ming Qi Bai

Doctoral Dissertations

Fiber optic chemical sensors based on the polymer bead swelling and shrinking have been evaluated and improved. The sensing element is a crosslinked polymer bead which swells or shrinks as a function of analyte. The change in bead size is coupled to the movement of a small mirror in front of two optical fibers. One fiber conducts light from a LED source to the mirror, the other fiber collects reflected light and carries it to a photomultiplier tube which serves as the detector. Changes in mirror position change the amount of light reflected into the collection fiber.

The variation in …

Polymer Substrates For Fiber-Optic Chemical Sensors, Amy Elizabeth Straub

Doctoral Dissertations

The primary goal of this research was to examine chemical and mechanical properties of polymers designed for a fiber optic chemical sensor based on polymer swelling. A second goal of this research was to develop a temperature sensor that could be used with other fiber optic chemical sensors.

Fiber optic chemical sensors have the capability for remote use, accuracy, sensitivity, selectivity, and ruggedness. Fiber optic sensors based on polymer swelling exploit the rugged features of polymers and fiber optic communications technology for use in remote sensing. A crosslinked polymer changes size in the presence of an analyte. As the polymer …

Interactive, User-Directed, Computer-Assisted Hplc Methods Development, Fang-Fang Qi

Doctoral Dissertations

An interactive, computer-assisted approach for determining multi-segment gradient elution profiles for High Performance Liquid Chromatography (HPLC) is presented. The approach is based on determining the gradient segment necessary to elute each solute at a user specified retention time. There are five main functions of this approach: (1) To inform the user of the possible retention time ranges for the solute that is going to be eluted for each elution step under both isocratic and gradient elution conditions; (2) To determine the required elution conditions, based on the user's desired retention times and the gradient elution shape; (3) To provide the …

New Approaches To Fiber Optic Chemical Sensors For Ions, Marian Frances Mccurley

Doctoral Dissertations

Two problems of current fiber optic chemical sensors (FOCS) were addressed in this research. First, an immobilized ligand was characterized as a possible reagent for detecting anions selectively. Second, a new approach to fiber optic chemical sensing based on polymer swelling was demonstrated.

The immobilized reagent explored for selective detection of anions is marketed as tris(carboxymethyl) ethylenediaminediacetic acid (TED). Characterization of this reagent showed that it is actually a mixture of ligands with ethylenediaminediacetic acid (EDDA) being the major species. Conclusive evidence was found in the EPR spectra. Several model ligands including a sample of TED from a private source …

Development And Application Of Artificial Intelligence Strategies To Solve Infrared Spectroscopic Problems, Barry J. Wythoff

Doctoral Dissertations

The ever-increasing power of modern infrared instrumentation, coupled with the decreasing number of experienced spectroscopists has created an imbalance between information generation and interpretation capabilities. At the same time, digital computers are being developed which continue to grow in storage and processing capabilities, and shrink in cost. Clearly, the computer may serve as a valuable tool to aid the analytical chemist in interpreting spectroscopic information. This dissertation deals with the development of new approaches to exploiting computer technology to interpret infrared spectroscopic data.

A large existing expert system for functional group analysis, PAIRS, has been modified to transfer the maximum …

Remote In-Situ Detection Of 2,4,6-Trinitrotoluene And Other Explosives Using Fiber Optics, Yunke Zhang

Doctoral Dissertations

The goal of this research was to develop methods for the in-situ determination of 2,4,6-trinitrotoluene (TNT) and other polynitroaromatic compounds in groundwater. The first approach was to use an adsorbent to preconcentrate TNT for direct determination. Poly(vinyl alcohol) was crosslinked with glutaraldehyde to form a clear gel that is transparent into the ultraviolet. The volume and swelling of the gel can be controlled by varying the amount of glutaraldehyde. The coefficient for TNT partitioning between the gel and water is 1.4. The gel offers important advantages as a matrix for chemical sensor development, but is not suitable for determining TNT …

Development Of A Glucose Sensor Based On Competitive Binding And Laser-Excited Fluorescence, Richard William Bauer

Doctoral Dissertations

An optical glucose sensor has been developed using competitive binding in conjunction with energy transfer. Sensor response is based on competition between glucose and dextran for a limited number of binding sites on the protein concanavalin A (conA). The system is optically monitored using fluorescent donor-acceptor dye pairs labeled to concanavalin A and dextran. When the dyes are sufficiently close, on the order of 50 A, energy is transferred from the donor emission band to the overlapping excitation band of the acceptor. This nonradiative, singlet-singlet transfer of energy enhances the acceptor emission at the expense of donor emission.

In absence …

Development Of An Analytical Method For The Determination Of Extractable Nitroaromatics And Nitramines In Soils, Thomas F. Jenkins

Doctoral Dissertations

An analytical method was developed to determine the concentrations of HMX, RDX, TNB, DNB, tetryl, TNT and 2,4-DNT in soil. The method relies on solvent extraction with analysis by reversed-phase liquid chromatography.

The extraction step was studied in terms of process kinetics and recovery. Two solvents (acetonitrile and methanol) and four extraction techniques (Soxhlet, ultrasonic bath, mechanical shaker and homogenizer-sonicator) were compared. Ultrasonic bath extraction with acetonitrile was selected based on extraction kinetics, overall analyte recovery, sample throughput, and instability of analytes at elevated temperature. The rate of extraction of analytes from field-contaminated soil was shown to be much slower …

Effects Of Experimental Conditions On The Sorption Of Organic Compounds To Soils And Sediments, Kathy Booth Britton

Doctoral Dissertations

Sorption is the basis for a number of techniques used to characterize solid particles. Because a number of techniques are based on sorptive interactions which are not fully understood, they are often plagued by experimental inconsistencies that are difficult to explain and frequently ignored. The purpose of this dissertation is to examine two techniques that are complicated by experimental inconsistencies--surface area measurements and the determination of distribution coefficients.

The apparent surface area of illite was measured by adsorption of a cationin fluorescent dye, Pyronin-y, from aqueous solutions in which pH and ionic strength were systematically varied. Estimates were highly dependent …

Selective Extraction Of Aquatic Sediments, Carolyn Kheboian Howard

Doctoral Dissertations

Sequential selective extraction procedures have been developed to determine the fate of potentially toxic trace metal pollutants in aquatic sediments. These multistep procedures operate through the application of reagents of increasing strength which solubilize different components of a sediment, thus releasing associated trace metals. Evaluation of the accuracy of these procedures is impossible with natural sediments because the location and concentration of trace metal pollutants are not known. Synthetic sediment standards must be made available to test extraction procedures.

For this research, model aquatic sediments are produced by combination of individually synthesized geochemical phases. Each phase is doped with a …

Chemical And Mineralogical Transformations Accompanying The Weathering Of Retorted Oil Shale, Irene Elizabeth Mcgee

Doctoral Dissertations

The development of western oil shale reserves will present major environmental problems due to the generation of huge quantities of mineral waste (retorted oil shale). The goals of this study are to investigate the extent of weathering within a retorted oil shale (ROS) spoil pile, in order to better understand the long term environmental impact of the material.

The U.S. Bureau of Mines operated a pilot scale retort facility in Rulison, Colorado from 1926 to 1929. Core samples from the spoil pile associated with this project were obtained by the U.S. Geological Survey, and serve as the basis for this …

The Role Of Histidine In The Mechanism Of Iron Release From Human Serum Transferrin, Donna M. Martin

Doctoral Dissertations

The role of non-coordinated histidines in the iron release mechanism of human serum transferrin has been investigated by chemical modification of the protein with ethoxyformic anhydride and aquopentaamine ruthenium(II), reagents specific for histidines under mild conditions. Kinetic studies of the iron release reaction at pH 5 under the action of different mediators e.g., PPi, Pi, Cit, ATP, GTP, and DPG, show that ethoxyformic anhydride imparts increased stability to the protein with rate constants for the C-terminal site decreased by factors from 2 to 10. The largest effects were seen with intracellular iron chelators GTP and DPG. A protonated imidazole group …

Interaction Of Polycyclic Aromatic Hydrocarbons With Dissolved And Sediment Associated Humic Materials (Nmr, Fluorescence), Thomas Donald Gauthier

Doctoral Dissertations

A fluorescence quenching method was developed for determining association constants of polycyclic aromatic hydrocarbons (PAH)s with dissolved and sediment bound humic materials. The technique is based upon the observation that PAH fluorescence in aqueous solution is quenched upon association with humic material. Association constants are derived from the fractional decrease in fluorescence intensity as a function of added humic material using Stern-Volmer plots. No separation is required and since the technique involves a ratio measurement the exact concentration of pollutant is not required. Anthracene-humic acid association constants normalized to the fraction of organic carbon in the sorbent (K(,oc)), determined by …

An Investigation Into The Analytical Utility Of Changes In Polarization Accompanying Analytical Derivatization Reactions (Fluorescence), Christopher P. Hallen

Doctoral Dissertations

Derivatization reactions between amines, alcohols and carbonyl groups with various reagents were studied. The goal of the work discussed in this dissertation was to generate basic data to know whether and in what context changes in fluorescence polarization are useful for following analytical derivatization reactions.

Reactions between primary amines and fluorescein isothiocyanate were initially studied. Changes in polarization were observed upon conjugation for many of the amines primarily due to changes in fluorescence lifetime. This reaction was also studied in varying amounts of glycerol to judge the effect of glycerol on the reaction rate. Optimum percentages of glycerol were determined. …

Computer Applications In Quantitative Epr Spectroscopy Of Metalloproteins (Ferritin, Apoferritin, Iron), L Paul Rosenberg

Doctoral Dissertations

This dissertation examines the use of computers in quantitative EPR spectroscopy. The computers used ranged from hand held calculators to large main frame systems. Applications discussed are protein assay calculations, an EPR minicomputer interface and software system and the modification of an existing EPR simulation program to include corrections for strains in the g and A tensors. The modification permits more accurate linewidth simulation for lines with large M(,I) values. The computer interface and software allows for the collection of EPR spectra, which can then be stored, scaled, added, subtracted (for comparison) and double integrated. The program enhances weak signals …

Fluorescent Probe Investigations Of Microenvironments Of Analytical Interest (Reversed-Phase, Polyethylenimine, Polarization), Sally Desmarais Dowling

Doctoral Dissertations

Fluorescent probes were applied to investigate three systems. Reverse phase chromatographic surfaces were studied using ion pairs. Variables were cation reagent structure and concentration, bonded phase (methyl, octyl, octadecyl, and phenyl), and solvent (water or methanol). Emission wavelength shifts for the anionic polarity probe, ANS, (8-anilino-napthalene-1-sulfonate) reflect the nature and extent of lipophilic interactions. Tetramethylammonium promoted ANS penetration into surface structure. Tetrabutylammonium overcame aqueous surface alkyl aggregation, which greatly enhanced ANS-surface interaction of C18. For the other phases at high cation concentrations there was lipophilic interaction between ANS and cation. High concentrations of small cations excluded ANS from the surface, …

Sensors Based On Immobilized Fluorogenic Reagents, Linda Anne Saari

Doctoral Dissertations

Sensors based on the fluorescence of immobilized fluorogenic reagents are prepared and their characteristics are defined. The fluorogenic reagent is chemically immobilized on a solid support and attached to the common end of a bifurcated fiber optic bundle. Fluorescence is excited through one arm of the fiber optic and observed through the other arm. The fluorogenic reagents fluoresceinamine, morin, calcein, and quinalizarin are immobilized on powdered cellulose via cyanuric chloride.

Consistent with previous studies of the pH dependence of fluorescein, the fluorescence from the immobilized fluoresceinamine sensor increases with pH. Immobilized fluoresceinamine serves as a viable pH sensor, but can …